Effects of physical exercise on outcomes of cardiac (dys)function in women with breast cancer undergoing anthracycline or trastuzumab treatment: study protocol for a systematic review

Background Cardiotoxicity is a known complication and one of the most adverse effects from the use of conventional treatments such as anthracyclines and trastuzumab in breast cancer (BC) care. This phenomenon has been associated with the restriction of therapeutic options and the increase of cardiovascular complications, which may compromise the survival of patients. Implementation of preventive strategies is an important approach for the management of this issue. Physical exercise has been proposed as a non-pharmacological strategy to counteracting cardiotoxicity. The aim of this protocol is to describe the rationale and methods for a systematic review of published randomized controlled trials (RCTs) that have analysed the effects of physical exercise on outcomes of cardiac (dys)function in women with BC undergoing neoadjuvant or adjuvant treatment containing anthracyclines and/or trastuzumab. Methods and analysis This is a protocol for a systematic review reported according to the PRISMA-P 2015 checklist. Randomized controlled trials (RCTs) will be included. The literature will be screened on MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials, ISI Web of Science and Scopus. The risk of bias of the included RCTs will be assessed using the Cochrane Collaboration's tool. The primary outcomes will be systolic function (left ventricular ejection fraction), diastolic function (E/A' ratio, deceleration time of early left ventricular filling, isovolumetric relaxation time, E/E' septal and lateral ratio) and myocardial deformation imaging outcomes (strain and strain rate [measured in longitudinal, radial, or circumferential directions]). Secondary outcomes will be cardiac biomarkers (troponin I or T, high-sensitivity troponin I or T, brain natriuretic peptide, amino terminal of B-type natriuretic peptide). Data will be descriptively reported, and quantitative synthesis will also be considered if the included studies are sufficiently homogenous. Discussion This systematic review will help to understand the effectiveness of physical exercise on counteracting cardiotoxicity related to anticancer therapies in women with BC. Systematic review registration PROSPERO CRD42018096060.